The principal investigator, Dr. James M. Greenberg, is currently an Assistant Professor in the Department of Laboratory Medicine and Pathology (Division of Immunopathology and Cancer Biology) and Department of Pediatrics (Division of Neonatology) at the University of Minnesota. His general research interest involve the study of human lymphoid ontogeny and developmental immunology. The general focus of this proposal is the analysis of human T cell gamma gene (T-gamma) and human T cell delta gene (T-delta) rearrangements and expression in acute lymphoblastic leukemia (ALL) and non malignant lymphoid progenitor cells blot analysis of DNA obtained from ALL cells and lymphoid progenitor cells that have been characterized by immunophenotypic analysis with a panel of monoclonal antibodies. Emphasis will be placed on correlating T-gamma and T-delta rearrangements and expression with different stages of lymphoid ontogeny. The specific characteristics of CD10 positive and CD10 negative thymocytes with respective T-gamma and T-delta rearrangements and expression will be analyzed. Emphasis will also be placed upon a group of leukemias with a CD3 positive, WT31 negative, CD4 negative, CD8 negative phenotype. Detailed immunophenotypic analysis of these cases will be performed to assess the heterogeneity of this group of leukemias, some of which appear to express the TCR gamma/delta antigen receptor chromosome 7 noted in the T-cell line MOLT-4 which may be associated with T-gamma. Similar analysis will be performed on a T-ALL that may contain a chromosomal rearrangement involving T-delta. All research activity will take place in Dr. Greenberg's laboratory and in the laboratory of Dr. John H. Kersey at the University of Minnesota. Dr kersey will serve as Dr. Greenberg's sponsor for this proposal. Dr. Kersey's laboratory has been actively studying the biology of human lymphoid leukemia and human lymphoid ontogeny for more than seventeen years. Other members of his laboratory are currently engaged in projects studying the molecular genetics of leukemia using techniques necessary for these studies including immunophenotypic analysis, Southern and northern analysis, genomic DNA cloning and Subcloning into phage and plasmid vectors, and DNA sequencing.